#include<stdio.h>

int flag = 0;

int Sum(int start, int end)
{
    int result = 0;
    for(int i=start; i<=end; i++)
    {
        result += i;
    }
    return result*flag;
}
int main()
{
    int start = 1;
    int end = 100;
    printf("I will begin!\n");
    int n = Sum(start, end);
    printf("running done,result is:[%d-%d]=%d\n",start, end, n);
    return 0;
}
